For many years, it has been debated whether or not strength training in children can be harmful, and whether it can be of any significant value to the young athlete.

However, overwhelming scientific evidence exists which shows that such training in childhood, if done in a reasonable way, may not only be quite safe, but also help the child and adolescent athlete succeed, and even improve our health and functional capacity as adults throughout life.

SIGNIFICANT STRENGTH GAINS MEASURED

Meta analysis studies, which look at all high quality studies performed to date, have revealed significant strength gains following strength training 2-3 times per week in pre-puberty aged children. Such strength gains have been found not to be associated with much increase in muscle bulk in children, but believed to be due to improved interplay between nerves and their target organ, the muscle, thereby activating more muscle fibers, or units (neuromuscular adaptation).

This is the same mechanism that occurs during the first few months of strength training in adults, which is later followed by increased muscle girth as the training continues, as a result of circulating muscle building hormones.

However, if the adult stops such strength training after a few months, he or she quickly loses the gained strength. The child, on the other hand, appears to stay stronger even after the training has been interrupted for longer periods of time.

IMPROVED MOTOR LEARNING

We have long known that it is in childhood, prior to puberty, that we have the greatest ability to improve motor learning-coordination. It has been found that such learning early in life can to a great extent decide a person’s movement capacity throughout life.

This is one of the reasons why it is so helpful for children to be exposed to a variety of physical activities and sports, and for sports training in childhood to be varied, and not too specialized.

It has also been found that lack of strength in childhood can interfere with a person’s ability to learn correct movements, and specific sports techniques. Therefore, lack of strength in childhood can negatively affect the child’s, and later the adult’s performance, and also significantly contribute to injuries.

STRENGTH TRAINING PREVENTS INJURIES

A recent meta analysis study, which analyzed 154 acceptable research studies, looked at the most effective strategies to prevent injuries in young athletes. The conclusion of this study was that agility and strength training was superior to all other injury prevention strategies.

Many studies have now showed that girls sustain more injuries than boys, in sports where quick muscle contractions and change in movement direction are required, such as basketball, soccer, gymnastics etc. It has been theorized that strength deficits in girls make them more vulnerable in such sports. I have previously written about the fact that this trend continues in girls even after puberty, as they often remain weaker than they need to be as the demands of their sports increase, whereas boys get progressively stronger much quicker due to puberty related increase in testosterone production.

As a whole, however the age of children where injuries peak is around 12-13, which is believed to be due to many sports requiring more of the young athlete around that age, but the child has not yet built sufficient strength.

IMPROVED BONE HEALTH FOR LIFE

It is known that we can build the most bone in childhood and adolescence, and that methods to do so will improve our bone health for life. The main method by which we can build stronger bone in young people, is exercise, and specifically high impact exercise such as jumping and plyometrics (recommended primarily during and after puberty due to its high strain) and strength training.

Although such training in adulthood is still effective in building bone, it cannot make up for the lack of bone strength that inactivity in childhood would have caused. We know that bone weakness, or osteoporosis, is a major health concern in the aging population, where fractures from falls is one of the leading causes of death.

RISKS AND RECOMMENDATIONS

Research data today have shown that appropriate strength training in children does not pose a risk to e.g. the bone growth plate, as had previously been speculated.

It has also been shown that children build as much strength by exercising with lighter weights as they do if training with heavy weights, which may not be as safe for them. Therefore, it is recommended for children to use light enough weights that they can at least perform 13-15 exercise repetitions. The optimal frequency of strength training in children appears to be around twice per week.

In conclusion, it has been recommended to include moderate strength training in children’s training programs, to make the training varied and include many forms of activities and movements, to design such exercise and practice in a playful and fun way, and when transitioning to puberty and beyond, also include plyometric training to promote explosive strength and bone mineralization.